358 CASE OF SAECINA VENTMCULI. 



texture, as iu the Goniums. The four-celled frustules corre- 

 spond to the cells or globules ; the tablet to the phycomater or 

 gelatinous matrix of certain of the ULVACEiE. 



The generation of Saecina is fissiparous, each individual 

 dividing into four. This is proved by the following circum- 

 stances : — 



Ist. Specimens are frequently met with, which, instead of 

 16 ternary squares and 64 ultimate ceUs, exhibit 64 ternary 

 squares and 256 ultimate cells. Such specimens are not, I 

 conceive, to be considered as individuals, in as much as — 1. 

 Their four component squares are very loosely connected to- 

 gether. 2. One or two of the ■ squares may be wanting, or 

 two or more of these may remain attached by the angles — an 

 arrangement never represented in the primary squares them- 

 selves. 



2d. Large specimens are occasionally met with, which 

 have most of the characters of composite individuals — that is, 

 of individuals about to divide into four. Such specimens do 

 not present 256, but only 64 ultimate cells, and these, ex- 

 hibiting appearances not easily defined, but apparently con- 

 sisting of four opaque spots, as if each cell were about to be 

 divided into four parts, or were in the act of producing within 

 itself four new cells. 



Such appearances rendered it difficult to say whether 

 certain specimens were simple individuals or composite — single 

 adults, or adults about to divide each into four young ones. 



I therefore conclude that a perfect individual Sarcina 

 consists of 64 ultimate cells, but that as soon as each of these 

 again divides into or produces four new cells, the individual 

 becomes composite, and may forthwith divide into four young 

 ones, each of these again to undergo the same quaternary 

 division. 



Such a mode of generation will account for what I fre- 

 quently observed — two, three, or four SAECiNiE attached by 



